This invention is of a mold or die for use in finishing tubular material of plastic and, by way of particular example, tube lengths for use as angiographic catheters. It will be appreciated that it is important that such tubular lengths have resistance to torsion so that the distal end responds as closely as possible to rotation at the proximal end. Further, it is important to have a catheter which is capable of delivering a relatively large volume, that is, one which has as thin a wall as possible so as to present a lumen of maximum diameter which is strong and smooth on the interior and yet which has the other qualities herein discussed. It is further important that such a tubular length do not promote clotting within the time of a normal medical procedure. As is appreciated, in use catheters are inserted axially into a tubular shaped zone of the body and a catheter should, therefore, be sufficiently stiff so as not to buckle under axial pressure and also be characterized by what is often termed as lubriscity. Additionally, the catheter when deformed should have a memory capacity so as to return to the correct shape after being straightened by a guide wire during positioning of the catheter. Also, a low coefficient of friction between the inside of the catheter and the guide wire as well as between the outside surface of the catheter at the entrance site and the body, termed lubriscity, is important. Generally speaking in making tube lengths for angiographic catheters, as well as other type tube lengths, it is desirable to have a smoothly finished accurately made product.
This invention is of a mold or die for use in making a catheter with such characteristics including a high tensil flexible plastic such as one of a material from the nylon family which may be covered by another biocompatible like urethanes properly treated to decrease the high coefficient of friction. The present invention provides a die or mold whereby a substantially larger lumen for a tube length may be produced without sacrificing the other characteristics set forth above. It will be understood by those in the art that this tool is useful in extruding such materials as are used in the art for such catheters which may have a radial opaque ingredient.